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Unread 09-21-2009, 10:42 AM   #1
BrockGrimes
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Engine sputters at half a tank

I'm pretty sure my gas gauge is working properly.
I'll be driving and the jeep will start to surge, spit, and sputter.
If i pump the gas i can kinda keep it going to a max of about 35mph or half throttle, but then eventually it'll shut off.
If it shuts off, it'll be hard to start for a couple min. then it starts and drives fine.
This happens around half a tank.

I was figuring crap in the gas but I run 2 fuel filters, 1 before fuel pump and 1 before carb, and it runs fine after I get it restarted.

WTFO?

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Unread 09-21-2009, 11:11 AM   #2
OlivergreenCJ7
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I wonder if it could be a float problem. Would make it easier knowing the engine, carb , etc.
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Unread 09-21-2009, 12:31 PM   #3
BrockGrimes
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258, carter carb, don't see it being a float as it runs fine as long as it's above half a tank.
Was thinking a pickup but it runs fine after it restarts.
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Unread 09-21-2009, 02:26 PM   #4
kercher
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how old are the fuel line hoses?
is there any gas in the fuel filter when it shuts off?
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Unread 09-21-2009, 04:45 PM   #5
zillla
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Maybe a hole in the fuel draw line in the tank. That's my guess.. When the fuel level reaches the hole the fuel pump can't pump enough cause it's coming out the hole and going back into the tank..
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Unread 09-21-2009, 04:53 PM   #6
gmakra
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Check your evaporate emissions canister filter on the bottom it maybe plugged.
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Unread 09-21-2009, 09:54 PM   #7
CJfreak
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X2 on what zillla said
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Unread 09-21-2009, 09:59 PM   #8
carnuck
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Make sure there isn't major vacuum when you loosen the cap next time it happens. If not, then it's not the tank holding the suction back. The "sock" in the tank collapses from being softened up by the MTBE and alcohol in fuel. Kind of like a sock stuck in the end of a vacuum. Nothing gets past it till you pull it out. I removed mine and left the one before the fuel pump.
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Unread 09-21-2009, 11:19 PM   #9
h2ojeep
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I had the same problem. the advise listed before, (hole in the line, vacuum, and canister filter) are all good ideas to check. I would add looking at the fuel filter just before the carb and make sure the return line is above the supply line (12 oclock) on the carburetor side of the filter and also pressure check your fuel pump (even if it is a new pump).

And check to make sure you dont have a small hole or loose conection in the line from the tank to the fuel pump (thus pulling air).(you will probably have to find some way to pressure the line someway to check that)

Recently someone ran a thread, and had connected a vacuum line to the return line on the filter (pulling a vaccum on the tank).... just fishing, but check to make sure

I would also ask to another symptom: does it act like a vapor lock? and work better when cooled down some? Does the problem go away when you fill the tank?
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Unread 09-22-2009, 11:21 AM   #10
BrockGrimes
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Like stated above runs perfect, idles great, till about half a tank, then it'll surge, sputters then cut off, I pump the gas and turn it over a couple times it starts then runs just fine till I get home or to teh gas station, I refill then drive it till the next time.

With the ability to drive it before and after it happens I'm not inclined to believe it's a fuel supply issue unless trash in the tank is causing it, but settles out of the way once it's shut off for a min or so. I have seen this happen on having to big a rubber line up near the pump or carb. Maybe the ignition module is getting to warm?

The rubber near the mech. pump and carb are newer, and the fuel filters also, the one at the carb is turned the right way and the lines are connected properly.
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Unread 09-22-2009, 12:06 PM   #11
LSUtiger
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Maybe try to run it without that extra fuel filter before the pump?
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Unread 09-22-2009, 01:20 PM   #12
John Strenk
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Quote:
Originally Posted by carnuck View Post
Make sure there isn't major vacuum when you loosen the cap next time it happens. .....
This almost sounds like you're not letting air into the tank becuase of a plugged vent. You just can't keep on sucking out gas without replacing it with air in the tank.

Try driving around with a loose gas cap. Just don't loose it though.
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Unread 09-22-2009, 04:09 PM   #13
BrockGrimes
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Wouldn't it stay vacuumed? After it shuts down I crank it a couple times and it starts.
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Unread 09-22-2009, 06:46 PM   #14
John Strenk
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Depends upon how well it's sealed. A perfect seal would stay vacuumed but nothing is perfect on a CJ. Your Gas cap could have a dry o-ring on it or some small seal will leak but not fast enough compaired when your driving.

Could also be a fuel hose that is collapsing when the engine is sucking gas harder. As soon as you stop, it gives a second for the hose to pop out again.

Then again it could be the first fuel filter plugging up also.
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Unread 09-23-2009, 06:23 PM   #15
BrockGrimes
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I added the first filter because I thought maybe it had trash getting through the filter by the carb.
I figured a vaccum issue would appear long before half a tank.
It's weird.
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